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Brain surface invasion and metastasis of murine malignant melanoma variants
Abstract:
Mouse B16 melanoma sublines were selected sequentially for their abilities to colonize brain meninges and leptomeninges of C57BL/6 mice. After 14 selections subline B16-B14b was established that formed significantly more brain tumor colonies than the parental B16 line. Examination of brains at various times after intravenous or intra-arterial injection of B16 cells by electron microscopy revealed that B14b melanoma cells lodged in small brain blood vessels, proliferated and invaded through vessel walls into brain parenchyma and also along small blood vessels at perivascular sites. Invasion into brain parenchyma was characterized by extension of melanoma cell filopodia resulting in fragmentation and sometimes enfulgment of glial and neural cells. Analysis of cell surface proteins of B16 melanoma sublines revealed increased exposure of a Mr approximately 90,000 glycoprotein on the high brain-colonizing cells. Antibodies against the Mr approximately 90,000 glycoprotein reacted with a variety of human melanoma cell lines and with some fetal and adult tissues, indicating that this melanoma-associated component is not species-, tumor- or tissue-specific. The glycoprotein could be a cell surface receptor important in the survival and growth properties of melanoma cells in brain microenvironments.
Insights
Researchers developed a highly brain-colonizing melanoma subline (B16-B14b) in mice. This subline invades brain tissue via cell filopodia and shows increased expression of a 90,000 MW glycoprotein potentially aiding brain metastasis.
Area of Science:
- Oncology
- Neuroscience
- Cell Biology
Background:
- Metastasis to the brain is a significant challenge in melanoma treatment.
- Understanding the mechanisms of brain colonization is crucial for developing targeted therapies.
Purpose of the Study:
- To develop and characterize a mouse melanoma subline with enhanced brain colonization ability.
- To investigate the cellular mechanisms underlying melanoma brain metastasis.
- To identify potential molecular targets associated with brain colonization.
Main Methods:
- Sequential selection of B16 melanoma sublines for brain colonization in C57BL/6 mice.
- Intravenous and intra-arterial injection of melanoma cells followed by electron microscopy.
- Analysis of cell surface proteins using antibody-based methods.
Main Results:
- Established B16-B14b subline demonstrated significantly increased brain tumor colony formation compared to parental B16 cells.
- B14b cells were observed to lodge in brain vasculature, invade through vessel walls, and infiltrate brain parenchyma.
- Melanoma cell invasion involved filopodia extension, leading to glial and neural cell fragmentation and engulfment.
- High brain-colonizing cells exhibited increased exposure of a ~90,000 MW cell surface glycoprotein.
- This glycoprotein is expressed across various human melanoma cell lines and tissues, suggesting a non-specific role.
Conclusions:
- The B16-B14b subline provides a valuable model for studying melanoma brain metastasis mechanisms.
- Melanoma cell invasion into the brain involves active cellular processes, including filopodia-mediated interactions.
- The identified ~90,000 MW glycoprotein may play a role in melanoma cell survival and growth within the brain microenvironment.
- This glycoprotein represents a potential therapeutic target for reducing melanoma brain metastasis.